从方法签名返回类型获取泛型类型的方法有多种,以下是其中一种常用的方法:
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
public class GenericTypeExample {
public static void main(String[] args) throws NoSuchMethodException {
Method method = GenericTypeExample.class.getMethod("exampleMethod");
Type returnType = method.getGenericReturnType();
if (returnType instanceof ParameterizedType) {
ParameterizedType parameterizedType = (ParameterizedType) returnType;
Type[] typeArguments = parameterizedType.getActualTypeArguments();
for (Type typeArgument : typeArguments) {
System.out.println("Generic type argument: " + typeArgument);
}
}
}
public List<String> exampleMethod() {
return new ArrayList<>();
}
}
上述代码中,我们通过反射获取了exampleMethod
方法的返回类型List<String>
的泛型类型String
。
import net.bytebuddy.ByteBuddy;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.ParameterDescription;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.dynamic.DynamicType;
import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
import net.bytebuddy.implementation.FixedValue;
import net.bytebuddy.matcher.ElementMatchers;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
public class GenericTypeExample {
public static void main(String[] args) throws NoSuchMethodException {
DynamicType.Unloaded<GenericTypeExample> dynamicType = new ByteBuddy()
.subclass(GenericTypeExample.class)
.method(ElementMatchers.named("exampleMethod"))
.intercept(FixedValue.value(""))
.make();
Class<? extends GenericTypeExample> loadedType = dynamicType
.load(GenericTypeExample.class.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER)
.getLoaded();
Method method = loadedType.getMethod("exampleMethod");
Type returnType = method.getGenericReturnType();
if (returnType instanceof ParameterizedType) {
ParameterizedType parameterizedType = (ParameterizedType) returnType;
Type[] typeArguments = parameterizedType.getActualTypeArguments();
for (Type typeArgument : typeArguments) {
System.out.println("Generic type argument: " + typeArgument);
}
}
}
public List<String> exampleMethod() {
return null;
}
}
上述代码中,我们使用了Byte Buddy库来生成一个临时的子类,并拦截了exampleMethod
方法的返回值,使其返回一个空字符串。然后,我们通过反射获取了该方法的返回类型List<String>
的泛型类型String
。
以上是两种常用的方法,可以根据具体的需求选择适合的方法来获取方法签名返回类型的泛型类型。
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